ASMultiplexImageNode.

Initial open-source release of ASMultiplexImageNode.  Documentation and
example code forthcoming.

Note:  ASMultiplexImageNode requires Xcode 6 to compile.  Tests are now
compiled against the iOS 8 SDK and run on iOS 7.1 and iOS 8.

AsyncDisplayKit.podspec

@@ -20,6 +20,9 @@ Pod::Spec.new do |spec|
       'Base/*.{h,m}'
   ]
 
+  spec.frameworks = 'AssetsLibrary'
+  spec.weak_frameworks = 'Photos'
+
   # ASDealloc2MainObject must be compiled with MRR
   spec.requires_arc = true
   spec.exclude_files = ['AsyncDisplayKit/Details/ASDealloc2MainObject.m']